2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 229-16
Presentation Time: 9:00 AM-6:30 PM


WILLIAMS, Kristal Ann, Environmental Science, St Mary's University, One Camino Santa Maria, San Antonio, TX 78228, ANDERSON FOLNAGY, Heidi, University of Montana Western, Dillon, MT 59725, ROCHA-CAMPOS, A.C., Instituto des Geosciências, Universidade de São Paulo, Sao Paulo, 05450-001, Brazil and COTTER, James F.P., Geology Discipline, University of Minnesota, Morris, 600 East 4th Street, Morris, MN 56267, kwilliams26@mail.stmarytx.edu

Striated surfaces, diamictites and other glaciogenic sediments of the Carboniferous Itararé Subgroup provide evidence of multiple glaciations near Witmarsum, Paraná State, Brazil. Although these glaciations are attributed to the Paraná lobe of the Gondwanan Ice Sheet, little is known about the geographic setting, depositional environments, flow characteristics or source area of this lobe. The goal of this study is to analyze diamictite units from differing stratigraphic levels to determine if provenance, source area, and glacial depositional conditions of the Paraná lobe change over time. Results may also aid in the identification of specific diamictite units within the repeating sandstones and diamictites of the Itararé Subgroup allowing for correlation between locations and better definition of the glacial advancements.

Ten diamictite samples from 7 different locations and stratigraphic horizons of the Carboniferous Itararé Subgroup were mapped, described, collected, and analyzed. Grain size analysis and point counts of the diamictite samples show very little differences in characteristics between 8 of the 10 different diamictite samples. The 2 samples that showed variation in their characteristics where obtained from clast rich diamictites that suggest unique glacial dynamics.

Research for this study was funded by a grant from the N.S.F.-R.E.U Program (NSF-EAR 1262945).